51.7% of the homes in the hamlet of Smithtown heat with fuel oil and 38.4% with utility gas, in a place where 88.7% of the 8,414 homes are detached houses. Those figures are for the hamlet alone: the unincorporated community of 12.1 square miles that includes the former Village of The Landing and part of San Remo. They are not for the Town of Smithtown, the much larger town that contains the hamlet along with Kings Park, St. James, Nesconset and most of Commack, each with its own numbers.
The hamlet was built mostly from the 1950s through the 70s. The median home dates from 1967; 37.8% of the stock went up in the 1960s, 15.8% in the 1950s and 14.1% in the 1970s, and 88.1% of occupied homes are owner-occupied. The electric company is PSEG Long Island, and National Grid gas runs down many streets but not all of them. On a street the gas main never reached, a house built around an oil boiler in the 1960s often still burns oil, and every draft in it is paid for by the gallon.
The houses we insulate in Smithtown
The hamlet is older than its median. The Landing governed itself as a village until it dissolved in 1939; the Smithtown Performing Arts Center on East Main Street was built in 1933 as a movie theater and has not been significantly altered since; and 503 homes, 6.0% of the stock, predate 1940, with 229 more from the 1940s. A house of that age usually has walls with no insulation at all and, if it is balloon-framed, cavities that run unbroken from the cellar to the attic. Those get blocked at the top and bottom before anything is blown in, and any knob-and-tube wiring goes to an electrician first.
The 1950s left 1,333 homes, mostly ranches and capes. The upstairs of a 1950s cape is often a pair of bedrooms under a shed dormer. Its weak spots are the dormer’s side walls, framed thin and exposed to the triangle of attic behind them; the short slopes where the ceiling follows the roof, packed with a batt and no air space; and the floor under the knee walls, which runs open from the cold eave into the warm house. A 1950s ranch has one long attic, and the trouble there is usually settled insulation over a ceiling full of unsealed holes.
The 1960s built 3,182 homes, the largest share of the hamlet: ranches, splits, high ranches and the two-story colonial, which gets its own section below. The 1970s added 1,186 homes in much the same mix. Those houses went up before New York had a statewide energy code: walls with thin batts or none, and an attic holding whatever the builder laid down, settled and disturbed since.
9.1% of the stock dates from the 1980s, 7.0% from the 1990s and 5.9% from the 2000s. Their walls are insulated, and their losses sit higher: vaulted ceilings, skylight shafts, attic ductwork. The 278 homes in buildings of ten to nineteen units and the 108 in buildings of fifty or more have envelopes that belong to their owners or boards.
The 1960s colonial: the overhang, the family room wing and the room over the garage
A two-story 1960s colonial looks simple from the street and hides several separate envelopes. Start at the front. Some have a second floor that overhangs the first. The floor joists of the bedrooms above run out past the lower wall, the soffit under the overhang is often a plain board, and the joist bays behind it are open to outside air. In a house built that way the front bedrooms are often the cold ones, because their floor is effectively outdoors. The fix is to open the soffit, block and seal each bay at the wall line, fill the overhang with closed cell foam or dense-packed cellulose, and close it back up.
Then the family room. A colonial of that era often has a one-story wing or a later addition off the back under a low roof of its own. Its small attic rarely has a hatch and does not connect to the main attic. Where the wing meets the two-story wall, the section of that wall inside the low attic is sometimes left without sheathing or insulation, and cold air in the wing’s attic moves straight into the wall and floor framing of the main house.
Then the garage. A two-car garage beside the house often has a bedroom, playroom or bonus room above it, sitting on a floor over unheated space, with knee walls and short slopes of its own. Owners describe that room the same way: cold in January, hot in July. Last is the main attic, with its pull-down stair, bath fans, plumbing vent and the chase carrying the boiler flue up from the basement.
We seal before we insulate
Insulation slows heat conducting through a surface; it does not stop air. In a two-story house warm air pushes out through the top-floor ceiling while cold air is pulled in at the basement and the overhang, every hour the heat is on.
In a Smithtown colonial the sequence works through each envelope in turn. In the main attic: seal the top plates, the chimney chase with metal and fire-rated sealant, the plumbing vent, the fan housings and the stair or hatch. In the family room wing: cut an access, seal the wall where the wing meets the house, then insulate. Over the garage: seal the garage ceiling, put an air barrier on the knee walls and vent channels in the slopes. At the front: block and fill the overhang. In the basement: seal and insulate the rim joist and the sill. Only then does the main attic get its full depth.
If a quote specifies a depth of insulation and never mentions air sealing, it is half a job.
What insulation costs in Smithtown
Most of our projects run between $3,500 and $12,500. In the hamlet the number follows the shape of the house. A 1950s ranch with one attic sits near the low end. A cape with a dormered upstairs costs more because the dormer walls, slopes and knee walls are all separate. A 1960s colonial with an overhang, a family room wing and a room over the garage sits higher, because each is its own small envelope with its own access. Spray foam pricing is laid out separately.
Open cell foam runs R-3.9 to R-4.2 per inch. Closed cell runs R-6.9 to R-7.1 per inch and also acts as a vapor retarder, which is why it costs more and why it is right in some assemblies and unnecessary in others. All products are manufactured in the United States and meet applicable building code and safety standards. ENERGY STAR says sealing air leaks and adding insulation can save up to 10% on annual energy bills.
Insulation rebates in Smithtown
The hamlet’s electric company is PSEG Long Island, and its gas company is National Grid, available on many streets but not every one. Since PSEG Long Island supplies the electricity, Smithtown homes cannot use NYSERDA’s Comfort Home program.
PSEG Long Island lists a $2,500 insulation rebate and a $1,000 air-sealing rebate for market-rate single-family homes, with higher amounts for income-qualified homes and homes in state-designated disadvantaged communities. The rebates are paid through PSEG Long Island’s participating contractors after a free Whole House Energy Assessment, which includes a thermal scan and a blower door test. Homes heated by oil, natural gas, propane or electricity all qualify. The insulation must be installed along with blower-door-assisted air sealing, and ductwork in unconditioned space must be duct sealed, which matters in a colonial with air conditioning ducts in the attic.
National Grid’s Long Island insulation rebate program is not accepting new applications; income-eligible households go through EmPower+. For a household under Suffolk County’s limit, NYSERDA’s EmPower+ program can pay for air sealing and insulation at no cost up to $14,000 for lower-income households (at or below $98,925 for four people), or half the cost up to $7,000 for moderate-income households (below $131,900 for four), through an EmPower+ contractor, with up to $1,600 more in federal HEAR funds for air sealing, insulation and ventilation. Long Island households should check eligibility on the MyEnergy portal.
NYSERDA’s Green Jobs–Green New York program offers unsecured loans of $1,500 to $25,000 over 5, 10 or 15 years, on the utility bill or as a monthly loan; PSEG Long Island customers must apply directly through PSEG Long Island, and loans are paid back. Every one of these programs pays through its own participating contractors, so check before you sign. The federal Section 25C insulation credit ended for work placed in service after 31 December 2025, and New York has no state tax credit for insulation. The details are in our New York and New Jersey rebate guide.
Code and climate in Smithtown
76.5% of the hamlet’s homes were built before 1980. New York’s first statewide energy code took effect on 1 January 1979, so the pre-war houses, the 1950s capes and the 1960s colonials were all built without one. Suffolk County is Climate Zone 4.
New construction now follows the 2025 Energy Conservation Construction Code of New York State, in force since 31 December 2025: R-49 ceilings, or R-38 across the full ceiling where uncompressed R-38 reaches full height over the wall top plate at the eaves; R-30 floors; basement and crawl space walls at R-15 continuous, R-19, or R-13 plus R-5 continuous; U-0.27 windows; and no more than 3.0 air changes per hour at 50 pascals.
Existing houses are treated differently. Unaltered parts do not have to comply, and New York’s code does not require a blower door test when you insulate an existing home. When an alteration exposes wall or roof cavities, those cavities must be insulated to full depth, so a family room wing opened for a renovation, or a room over the garage stripped to its framing, gets filled completely. ENERGY STAR recommends R-60 for an uninsulated attic in this zone and R-49 where 3 to 4 inches are already there.
Common questions about insulation in Smithtown
Do you install insulation in Smithtown, NY?
Yes, across the hamlet of Smithtown: the 1960s colonials, splits and ranches that make up 37.8% of its homes, the 1950s capes and ranches, the 503 houses built before 1940, and the newer houses from the 1980s on. We also work in the rest of the Town of Smithtown, including Kings Park, St. James and Nesconset, which have their own pages. We do not take on the envelopes of the larger apartment buildings. If you are not sure your home fits, ask on the phone.
How much does insulation cost in Smithtown?
Most projects run $3,500 to $12,500. A 1950s ranch with one attic is usually near the low end. A cape with a dormered upstairs costs more because its dormer walls, slopes and knee walls are separate pieces of work. A 1960s colonial with a front overhang, a family room wing and a room over the garage sits higher, since each is its own small envelope. Pre-war walls add blocking and dense-packing. The scope and price come in writing after a free walk-through.
Are there insulation rebates in Smithtown?
Yes. The hamlet is PSEG Long Island territory, and PSEG Long Island lists a $2,500 insulation rebate and a $1,000 air-sealing rebate for market-rate single-family homes, higher for income-qualified homes, paid through its participating contractors after a free Whole House Energy Assessment. Oil heat does not disqualify a house. Comfort Home is not available to PSEG Long Island customers. EmPower+ serves income-eligible owners and renters, and Green Jobs–Green New York offers loans. The federal 25C credit has ended, and New York has no state insulation credit.
The bedroom over our garage is cold in winter and hot in summer. What fixes it?
Usually three things done together. The garage ceiling under the room is sealed at every gap and filled, because that floor sits over unheated space and most have only a thin batt. The knee walls on either side get an air barrier on their back face and insulation, and the floor bays under them are blocked where they run out to the eave. The short slopes get vent channels and are insulated to depth. Adding a bigger heater or a register without fixing the envelope only moves the problem.
Free energy audit in Smithtown
In the hamlet we walk a house envelope by envelope. In the main attic we look at insulation depth, the chimney chase and the fan ducts; then we find a way into the family room wing’s attic, which is often the first time anyone has seen it; then the room over the garage, its knee walls and the garage ceiling below; then the front overhang and the basement rim. If the main attic is fine and the cold comes from the overhang, we tell you. Then a written scope and a price, with no charge and no obligation.
Call 914-825-6824 or use our contact form. Open 8am–8pm, seven days. We work out of New Rochelle, NY with a 100-plus in-house crew that never subcontracts.
Learn more
- Insulation contractors across Suffolk County
- Insulation in St. James
- Insulation in Kings Park
- Insulation in Nesconset
- Garage ceilings and rooms over the garage
- Attic insulation
- Recommended R-values for New York